The invention relates to a switchback transport mechanism for switching back a sheet being transported along a transport path. The invention further relates to an image forming apparatus provided with such a switchback transport mechanism.
There has been a growth in the number of image forming apparatus provided with a switchback transport mechanism that switches back a sheet by transporting the sheet forwards and then backwards. In image forming apparatus with duplex-printing features, for example, a sheet, after passing through an image forming section, is switched back by a switchback transport mechanism and then guided again to the image forming section. Such image forming apparatus use various different methods devised of switching back a sheet by the switchback transport mechanism. JP S58-207247A discloses a switchback transport mechanism having a half-moon roller that is arranged along a switchback transport path for the purpose of facilitating sheet switching-back.
With the prior art mechanism, however, it is impossible to guide a sheet into a switchback section until an immediately preceding sheet is switched back and ejected out of the switchback section. This results in relatively long intervals at which a series of sheets to be successively switched back are transported, thereby preventing an image forming process from being speeded up.
In view of the foregoing problems, a feature of the invention is to provide a switchback transport mechanism that allows sheets to be transported, and switched back, with improved efficiency, and an image forming apparatus provided with such switchback mechanism.